Some video transmission systems merge video and content to be shared into one video stream. In such systems, the video stream may be transmitted using standard video codecs and streaming protocols. Upon receipt, the video and content are displayed for view on a web browser. These systems require no processing of the video stream at the viewer site aside from the processes related to receiving and displaying. Such systems typically treat the combined video and shared content similarly regarding methods of compression, transmission, reception, and display even though different methods may be more efficient or otherwise more suitable for each of the components that went into the video stream.
Where transmission systems send video and content separately, the video itself is typically transmitted using processes that treat the pixels of the video uniformly. Thus, such current transmission systems do not exploit the potential provided by user-extracted video to differentiate between an image part and a background part of the user-extracted video, or between an image part and a non-image part of a user-extracted video combined with another video or other content. Also, current video transmission systems do not support the use of an alpha mask (also known as an “alpha channel”), though there have been efforts to modify current systems to support WebM video with an alpha channel for VP8 video.